The present invention is relating to a fixture for an electrical device in general, and more particularly to a fixture for rapidly, easily and stably assembling a heat dissipating device and an electrical device.
It is well known that an electrical device of high power such as CPU will produce much heat in run. In order to prevent damaging an electrical device due to overheat, a heat dissipating device is necessary to be installed for conducting heat from the electrical device. In general a heat dissipating device is a heat sink, a cooling fin or a cooling fan etc, and is directly installed above a heating electrical device by wedging method for conducting or dissipating heat. Therefore, a heat dissipating device needs a stable fixture to be closely installed above an electrical device for a good effect of cooling.
As shown in FIG. 1, a fixture 10 for adhering a heat sink 20 on the upper surface of CPU 32 is disclosed in Republic Of China (Taiwan) Patent Publication No. 254,450 xe2x80x9cfixture for a CPU heat sinkxe2x80x9d. The fixture 10 includes a tenon 11 that has a head 12 at one end and the other end is an arrow-shaped inverse-pin 13, wherein a spring 14 is employed around the tenon 11. While pushing the tenon 11, the inverse-pin 13 downward passes through through hole 21 of the heat sink 20 and through hole 31 of a PCB 30 (printed circuit board), in which the heat sink 20 is located on the upper surface of CPU 32 and the CPU 32 is bonded on the PCB 30. Due to an upward spring force from the spring 14, the tenon 11 inversely wedges the heat sink 20 and PCB 30. However, while pushing the tenon 11 by hand, it is unable to make the tenon 11 precisely position and stably wedge due to inclination or shake.
As shown in FIG. 2, a fixture 40 that comprises several pin devices to assemble and fix the heat sinks 50 on the CPU 62 of a PCB 60 is disclosed in Republic Of China (Taiwan) Patent Publication No. 454,899 xe2x80x9cfixture (III) for a CPU heat sinkxe2x80x9d. The pin device is a tenon 41 that has a head 42 and an insert 43. A spring 44 is employed between the head 42 and the insert 43, and a sleeve 45 covers the spring 44 corresponding to the pin device. A through hole 46 is formed at the center of bottom ring of the sleeve 45 for passed through the tenon 41 so that the tenon 41 passes through the through holes 51 of heat sinks 50 and the through hole 61 of PC board 61 for assembling and fixing the heat sinks 50 and the PCB 60. The head 42 of the tenon 41 must be smaller than upper opening of sleeve 45 for passing through the sleeve 45 while pushing the pin device, and larger than the opening of spring 44 for pushing the spring 44. However, the tenon 41 and the sleeve 45 of fixture 40 are usually manufactured by plastic injection molding. If the head 42 of tenon 41 deforms due to changing of temperature while running CPU 62, the head 42 may be unable to pass through the sleeve 45 because of that larger than upper opening of sleeve 45 or unable to push the spring 44 because of that smaller than the opening of spring 44, so that the fixture 40 is unable to be used normally. Further as shown in FIG. 3, it is a known fixture 70 for a CPU heat sink. The fixture 70 includes a tenon 71 that has a head 72 and an insert 73, and a sleeve 75. The tenon 71 combines with a conical spring 74 that is covered by a sleeve 75 between the head 72 and the insert 73. A ring trough 76 is formed around the lip of the sleeve 75 against the large opening 74a of conical spring 74. As shown in FIG. 4 while pushing the tenon 71, the head 72 of the tenon 71 compresses against the small opening 74b of conical spring 74 to make conical spring 74 stretch, so that the insert 73 of the tenon 71 passes through the through holes 81 of heat sinks 80 and the through hole 91 of PCB 90 to closely wedge the heat sinks 80 on the CPU 92 that is bonded on PCB 90. However, if the small opening 74b of conical spring 74 expands a little, the head 72 of tenon 71 is unable to block the small opening 74b of the conical spring 74 but passes through the conical spring 74. Moreover, while pushing force is big the large opening 74a of conical spring 74 easily deformed to make conical spring 74 jump out from the ring trough 76 of sleeve 75 that is against the large opening 74a of conical spring 74. Therefore, the fixture 70 cannot be used durably.
It is a first object of the present invention to provide a fixture for an electrical device to prevent a spring jumping out from the pin. A ring block is used to limit the spring inside the pin casing. Typically, the ring block is installed against a press portion of a pin to make the spring be compressed.
It is a second object of the present invention to provide a durable fixture for an electrical device. A ring block is installed between press portion of pin and spring and is limited inside pin casing by flange of the pin casing so as to ensure the spring keeping inside the pin casing.
It is a third object of the present invention to provide a fixture for an electrical device that includes a pin casing with round-wall. The round-wall forms at least a flange. A gap is formed at the two sides of flange respectively to elasticized the flange for stuffing the ring block inside the round-wall of pin casing.
It is a fourth object of the present invention to provide a fixture for an electrical device that includes a ring block fastened inside the pin casing. By means of the press portion of pin, the ring block is pushed to make the spring be compressed so that the wedge portion of pin is able to wedge the electrical device closely. Therefore, the effect of easily, rapidly and stably wedging the electrical device can be reached.
According to the present invention, a fixture for an electrical device comprises a pin casing, a spring, a ring block and a pin. A pin casing has a bottom and a round-wall to form a containing trough for placing the spring. The bottom forms a hole and the round-wall forms at least a flange. It is preferable that a gap is formed at the two sides of the flange respectively to make round-wall outward expand for stuffing the ring block inside the pin casing. Also the flange limits the ring block without jumping out. The ring block has a through hole and the pin passes the through hole of ring block, spring and the through hole of bottom of pin casing to combine pin casing, spring, ring block and pin together. The pin has a press portion and a wedging portion. The press portion is used for pushing the ring block to compress the spring. The wedging portion is used for securely wedging an electrical device.